The present invention relates generally to a process for the fabrication of rubber strips from a non-vulcanized rubber mixture by cut-off of a sectional width of a layer of the rubber mixture which is adherent to the surface of a roller to form a web, and wherein the web is being delivered from the side of a rolling mill or calender at the processing temperature. The process is particularly adapted for treating the web of material as it is being prepared for cooling to ambient temperature by passing through a cooling chamber or apparatus.
At the present time, there are known processes of the general type mentioned above, wherein the cut-off sectional width or web of the rubber mixture layer corresponds to the desired width of the finished strip. This strip width corresponds to only a small fraction of the total axial length of both rollers of the rolling mill so that, because of the very small amount of rubber mixture which is being taken off the mill per unit time, there results a longer mixing time for the mixture than would normally be required for thorough mixing and kneading.
In accordance with another known process, the layer of rubber mixture, as distinguished from the previously mentioned known process, is cut-off at an essentially greater width to form a pressed rubber sheet or web having an overall width corresponding to an intergral multiple of the width of the desired strips. This pressed rubber sheet is then fed as a web into a cooling apparatus, in its full width, and, after having been run through the cooling apparatus, is cut off in its cooled condition transversely to the web direction into strips or strip segments of desired width. In the cutting operation, a separate machine equipped with die punches or circular knife blades is normally used, wherein the cut-off lines do not extend clear across the full width of the pressed rubber sheet, but rather are made along its length at somewhat less than the width of the pressed rubber sheet forming the web. Furthermore, the cuts start alternately from one and then the other edges of the web so that a labyrinth-type pattern is formed.
In separating the structure obtained from such a cutting operation, one accordingly obtains from the pressed rubber sheet, a single contiguous strip, with individual strip sections having a length corresponding to the original length of the web hanging together, end-to-end, in zigzag fashion. However this does not affect the processing that follows, for example, the feeding of the entire strip into an extruder, because any supplementary sections of rubber which may be present at the junction points of the strip sections are evenly distributed. Nevertheless, the division of the pressed rubber sheet or web mentioned, corresponding to the "labyrinth" section also mentioned, requires not only an additional work step or operation, but also a very expensive machine.
A further modification or development of the lastmentioned known process consists in dividing the pressed rubber sheet or web, after cooling, along its lengthwise direction into a plurality of non-connected process strips of desired width, wherein the length of each such strip corresponds to the length of the pressed rubber sheet. A separate machine is used, and the same problems appear here as in the case of the above-mentioned process.